Chemical Basis of LifeA Review of Some of the Basic Chemical Principals

Elements and Compounds

•Most Common Elements that make up living things▫C, H, O, N, ▫3.1.2 Ca, P, K, S, Na, Fe, Cl, Mg, and Trace

elements Give an example of a role for each in Prokaryotes,

and Plants/Animals

Roles of Other Elements

•Sulfur: Disulfide Bridges in Protein Tertiary Structure

•Calcium: Muscle Contraction, Neurotransmitter release.

•Phosphorus: Phosphate groups•Iron: Hemoglobin•Sodium: Nerve Conductioin

Atoms and Molecules•Atom – Smallest possible unit of matter

that retains the properties of its element▫Subatomic particles

Protons (mass is 1.007 dalton) about the mass of a hydrogen atom or 1.67 x 10-24 g

Neutrons electrons

Atomic Models

Atom

Atoms and Molecules

•Atomic number – same as the number of protons and electrons 8 O

•Atomic mass – number of protons and neutrons 16 o▫Can figure out the number of neutrons by

subtracting the atomic number from atomic mass

Isotopes•Atoms of the same element that have

differing number of neutrons.▫Naturally they have mixtures of isotopes▫Some are radioactive▫Uses

Dating Half life

Tracers

Uses of Radioactive Isotopes

Bonding•Ionic bonds

▫Ion is a charged atom or molecule▫Anion- gained one or more electron▫Cation- lost one or more electron▫Ionic bond is formed by an electrostatic

attraction after complete transfer of electrons.

▫Ionic compounds are called salts

Ionic Bonds

Ionic Compounds

•Some have different ratios▫MgCl2

▫NH4Cl

Bonding•Covalent

▫Sharing a pair of valence electrons

▫Strong Single Double Triple

Single and Double

Bonding•Electronegativity

▫The more electronegative an atom the more strongly it attracts shared electrons

▫Scale determined by Linus Pauling O = 3.5 N = 3.0 S and C = 2.5 P and H = 2.1

Bonding

•Non-polar and polar covalent bonds▫Non-polar – equal sharing of electrons▫Polar- unequal sharing

Due to different electronegativities H2O

Polar

Weak Bonds and Life

•Weak bonds are very important to living things.▫Hydrogen bonds▫Ionic bonds in

water (weak)▫Van der Waals

Water’s Shape

Biological Shapes are Critical

Biological Shapes are Critical

Knowing shapes can help